Hydrometallurgy of copper.



w. N. nossmane al G. E. SHERIDAN.

HYDROMETALLURGY OF COPPER. APPLICATION FILED 0:0.20. m1.

1 ,292QO75 Patented Jan. 21 1919.

154mm; TANK Cu 504 sou/rm 'LEACI/ED Dill/N65 SOURCE OF PRESSURE or HEA Tani mfssung sou/m OFHEAT Mp5 6A5 H35 gals/Mm VACUUM FILTER FEGENERA TED Hz 504 C02 5 PFECIPITATE- 'ablo .Othors skillod in tho being regonoratod UNITE swans ATENT omno.

WILLIAM N. ROSSBERG AND GUY E. SHERIDAN, OF BUTTE. MONTANA.

HYDROMETALLURGY OF COPPER.

Specification of Letters Patent.

Patontod Jan. 21. 1919.

Application filed December 20. 1917. Serial No. 208,021.

Do it known that wo. 'naani Rossnnno and GI'Y E. Suiunnax. both oitizons ot tho l'nitod Stat'os. and both rosidonts ot' Butto. oounty of Silrorbow. and Stato of Montana. havo inrontod oortain now and usoful Improroinonts in Il \'dromotallurgv ot' '(oppor; and we do horobv doolaro tho t'ololozit. and oxaot dosuoh as will onatt to \\'llltl| it apportains to mail and uso tho. saino.

Tho prosont invontion rolatos to tho rooovory of ooppor from oxidizod ooppor oros prinoipally in tho form of ouprous sultid: and moro partioularlv it rolatos to suoh rooovory by tho loaohing ot tho oxidizod ooppor oros with sulfurio acid and tho rooo\'or of tho ooppor prinoipallv as tho ouprous sultid from thorosulting sult'ato'solutions. tho arid hold in ooinbination with tho ooppor and boing thus niado availablo for loaohing furtlu amounts of tho oro.

\Vo havo found that tho rooovory ot roppor as sultid from ooppor sulfato solutions (Jail be ofi'ootod with about ono-halt' tho amount of hydrogon sultid or its oquiralont prooipitating agont. commonly oinplo \'od it' the precipitation is oarriod on in tho prosonoe of sutiioiont sult'ur dioxid (sult'urous acid) to giro tho propor roduoing oonditions: and that undor thoso oonditionstho ooppor will be prooipitatod in tho, ouprous oondition. as ouprous sultid. and additional ainounts ot'sult'urio arid will at tho sanio timo bo fol-mod from tho sul'turous aoid.

'lho aooompanying drawing tliagranunat ioally illustra'tos, by moans of a-oonrontional flow shoot. an arrangoniont of apparatus for tho oxooution of tho various stops of tho method of our prosont. inrontion. 'lho various -troat-mont stops and the apparatus o|n ployod aro appropriately logendod on tho drawing. and tho souroo, dostinatiou and dirootion ot' travol of tho various produots produood in tho oourso of tho proooss aro dosignatcd by linos and arrows. 'lho sig- DifiPtltit)". of tho logonds. linos and arrows in, tho drawing will bo oloar from tho. following dosor-iption.

In tho oarrying out of tho invention, tho oxidizod ooppor oro, which may be a native lowing to ho a full. soription of tho invention.

.tions whioh may rosult from any suitablo inannor as by passing tho oro. or a roastod sultid oro or oto.. is loaohod with sulfuric aoid of any dosirod s'trongth. 'lho aoid may advantagooltslv bo that whioh is rogenoratod later on in tho proooss. Tho loaohing ma} be otl'ootod or promotod b agitation with air or moohanioallr. b poroolation. or by othor suitablo mothods or 'lho solution oan bo progrossii'oly inoroasod in strongth b oxtraoting t'rosh lmtohoS of oro with tho moro diluto solutions. in oase solutions of tho dosirod strong-Hr aro not arailahlo b a singlo loaohing'oporation.-

wators and tho diluto soluwashing out. or oxtraoting tho last' of tho ooppor from proriouslr loaohod batchos may bo usod in ltttilliug frosh batohos. Tho ooppor olution is soparatod l'rout tho ganguo mattor bv dooantation or filtration. Solutions of high ooppor ooutont insuro ooonomioal handling.

it tho ooppor sult'ato solution oarrios oonsidorablo iron. this should bo ronio,\'od. o. r by adding ooppor ()Xigl and agitating with air. or by :u'ldingatrV othor suitablo baso. or by othor moans l\'llti\\'ll to tho art: and tho prooipitato roinorod from tho solution by dot-ant ing or tiltoring. 'lhis proooduro. howo\'or. will usually bo norossarr only whon oousidorablo iron is prosont.

.\l"tor having obtainod tho ooppor solution it is improguatod with sult'ur dioxid-gas in gas 'lilllll ltl ol suitablo aporturos in tho bottom ol' \uts or tanks oontaining tho propor solution and thorob) oausing it to bubblo up through tho solution. or by spraying'tho ooppor solution down a towor against an uptlowing st roam of .tho sulfur dioxid gas. or by othorwiso"bringing about the not-ossar intorinixturo of tho liquor and gas.

'lho ooppor solution. iinprognatod with tho sult'ur dioxid gas. is thou troatod with h \'drogon sultid gas. 'lho quantity of hydrogon sultid roqui rod is dotorniinod by tho amount of ooppor prosont in solution. taking into aooouut that tho ooppor is to be prooipitatod as tho ouprous sultid so that only ono-halt' tho prooipitating agont is uooossary that would bo roquirod for tho prta'ipitation. in tho usual way. of tho ouprio sllllitl. The

So also. wash through a troatinont of the liquor with hydrogen sullid oombinations thoroof.

i oonoontrate,

' be used for connecting may be brought about by injecting or bubbling the gas into and through the liquor, or in absorption towers, or otherwise, in a manner analogous to that used in the impregnation with the sulfur dioxid The reactions take place in either cool or warm solutions but are materialli hastened by the aid of heat or pressure. The heating of the solution or liquor may be done economically by using the hot sulfur dioxid gases from roasting furnaces or sulfur burners.

The impregnation of the copper sulfate solution with sulfur dioxid, and the precipitation of cuprous sulfid by hydrogen sulfid may both take place, in accordance with our present invention, and pressure. v While heat promotes the reactions, good results are attained at normal temperatures. Pressure, like heat, aids the reactions, but is not essential and can be dispensed with. either heat or pressure a slight increase in temperature above the normal, for example, a temperature not exceeding 160 F and a pressure not exceeding 30 to 4:0 lbs. per sq. inch are ample. The use of hot sulfur dioxid gas from roasting furnaces or sulfur burners for the impregnation of the copper sulfate solution may be used for heating the solution, or the precipitation vat may be jacketed for the use of any suitable source of heat. The desired pressure may be conveniently obtained as a result of the hydrogen sulfid gas used, or any suitable means may the interior of the closed precipitation vat to a source of pressure or to a source of heat and pressure. A slight excess of sulfur dioxid should at all times be present so as to insure the precipitation of the copper in the cuprous condition. In order to insure economical absorption of the.sulfur dioxid gas in solutions of high copper content, it may be necessary to alternate the impregnation of the copper solution with sulfur dioxid gas and with hydrogen sulfid, this impregnation being effected by such procedures as have been outlined above.

From appearances it would seem that copper is probably first precipitated to a certain extent metallic copper which is almost instantly converted to the cuprous sulfid. While the intermediate compounds formed by the action of sulfur dioxid and hydrogen sulfid gases upon sulfate of copper in'solution are very unstable, making these reactions problematical, the amount of copperprecipitated and the amount of acid formed from known quantities of sulfids indicatesthat the following equation is a probable summation of the reactions; but we do not wish to limit ourselves by any theoretical explanation of What the actual at ordinary temperature When it is desirable to use by the use of gaseous reaction may be, and we give this equation merely asfa probable summation and explanation of the reactions which take place.

the copper as sulfate from the ore. The

ols an so That is to" in dissolving process is thus one which produces add-itional amounts of sulfuric acid from the sulfur dioxid used, as well as one which results in the recovery of the copper as the cuprous sulfid. This acid which is regenerated, or which is generated, during the precipitation, after separation from. the precipit-ate, is available for leaching fresh quantities of ore forthe production of further amounts of copper sulfate solution; and it is also available for the treatment of sulfids such as iron sulfid or calcium sulfid in order to generate therefrom hydrogen sulfid.

Instead of using gaseous hydrogen sulfid for the precipitation of the copper, the sulfid may be set free within the solution by adding a decomposable sulfid, such as an alkali or alkaline earth sulfid, or even iron sulfid, to the solution, and decomposing it therein and forming the hydrogen sulfid therefrom. For example, a finely divided sulfid, preferably calcium sulfid, is added to th solution of copper sulfate, in quantities determined by its precipitating power and the amount of copper to be precipitated, keeping in mind that the copper will be precipitated in the cuprous condition so that only about onehalf of the precipitating agent is necessary that would ordinarily be used in the precipitation of cupric sulfid. added directly to the solution if free acid and ferric sulfate are absent; if, however, the copper solution contains free acid, or anything that will (lecmnpose the sulfid, such as ferric sulfate or an cid sulfate, the solution should be impregiiated with sulfur dioxid previous to divided calcium sulfid or other sulfid. If the solution is free from acid, ferric sulfate, etc... it may be impregnated,with sulfur dioxid gas in tanks or towers or otherwise after the addition of thecalcium sulfid. In other words, the hydrogen sulfid gas will be liberated within the solution and will act as a precipitant therein. As with precipitating hydrogen sulfid, the precipitation by the hydrogen sulfid generated in the solution may be pmnnoted by The sulfid can be the addition of the'fincly is recovered as the cuprous sulfid.

cated by those indicated by the following equation:

and antimony) e. 9.,

stirring or agitating or by otherwise securing the necessary intimacy and uniformity of distribution and inter-mixture of the precipitating agent within the solution.

The decomposition of the added sulfid will be accelerated by the presence of free acid. Heat will also hasten the reaction, as in the case of precipitation of they copper by added hydrogen sulfid gas, and the heating may be effected in the same or similar manner to that previously referred to. Mechanical agitation, as noted above, also facilitates the keeping of the undecomposed sulfid in suspension and in contact with the copper in solution.

he reactions which take place, as indi-- the results obtained, seem to be As indicated by this equation the copper is precipitated together with calcium sulfate in the form of a composite precipitate containing about 40% copper. At the same time, the sulfuric aci is regenerated to the extent that it has been held in combination with the copper, and this acid is thus made available, after separation from the precipitate, for leaching fresh quantities of ore. The-process of the present invention may be utilized for the removal and recovery of copper (and other metals belonging to the hydrogen sulfid from liquors obtained in the leaching of zinc ores with sulfuric acid, and the zinc sulfate solutions thereby purified at the same time that the copper The zinc sulfate solutions containing copper sulfate, may thus be freed from the copper, and the copper recovered'as a precipitate, in the manner above described, by treating the solution with hydrogen sulfid in the presence of an excess of sulfur dioxid, a sufficient amount of acid being present to prevent precipitation of the zinc sulfid.

The sulfur dioxid gas which is used in the process of the present invention may be produced in any'suitable or well known manner. It is usually available as a waste product from roasting operations, and the roaster gases may be the source of this gas. Where such roaster gases are-not available, the sulfur dioxid may be prepared by the combustion of sulfur or pyritcs, or from special roasting operations.

The hydrogen sulfid gas, when gaseous hydrogen sulfid is used, can sin'iilarlybe prepared from any of the common or a vailable sources of this gas. It may thus be generated from iron sulfid by the action of sulfuric acid, and, for this purpose, a part of the regenerated sulfuric acid can its combination with the group, such as arsenic V be used. Inasmuch as the precipitation by gaseous hydrogen sultid results in the generation of one and one-half times as much sulfuric acid as was combined with the copper, and as is required for the extraction of a corresponding amount of copper, a considerable amount of sulfuric acid is thus available for use for the generation of hydrogen. sulfid, or for which it may be desired.

Accordingly, from one view point, the process of the present invention is a process for the manufacture of sulfuric acid from sulfur dioxid. the amount of acid thus made amounting, as above pointed out, to about one-half of that which is set free from copper, and being in addition to that which is so set free from its combination with the copper.

Where, instead of gaseous hydrogen sulfid, its equivalent in the form of iron sulfid or an alkali or alkaline earth. sulfid is used, and decomposed within the solution by sulfurdioxid or other acid or acid salt, there is still regmerated an amount of sulfuric acid corresponding to that in combination with the copper and 'to that required for the leaching of a corresponding amount of copper from further batches of the oxidized ores.

It will thus be seen that the process of the present inventionis one of notable economy, a minimum amount of hydrogen sulfid gas or its equivalent being required for the precipitation of the copper as cuprous slilfid; this amount being, as above pointed out. about one-half of that commonly used in the precipitation of the ordinary copper (cupric) sulfid from copper sulfate solutions. lVIoreover, since the precipitation is effected with a minimum of the hydrogen sulfid, a smaller amouutof this gas is required to be absorbed by the solution, or liberated therein, with the result that the absorption takes place more readily and with the further important result that less of the hydrogen suliid has to be handled so that large excesses of the gas can be avoided. There is thus a greater eiliciency in the use of the hydrogen sulfid orof, the equivalent suliid precipitating agent, as well as a notable economy in the amount of the precipitating agent required.

Furthermore, it will be noted that the precipitation of the lid ((IlnS) instead of as the cupric sulfid ((YuS) results in the production of a precipitate which is richer in copper.

The cuprous sulfid precipitate obtained is easily treated by familiar metallurgical operations for the recovery of metallic copper therefrom. xlvhere the precipitate is obtained in the form of a composite precipitate of cuprous sulfid and calcium sulfate,

other purposes forv co er as the on )roiis sulhydrogen sulfid, over fate,

manner for the recovery of the metallic copper therefrom.

Aside from the economy and etiiciency incident to the practice of the invention in the manner described, the resulting solution is one relatively or substantially free from hydrogen sultid and its accompanyim objectionable features. tion of this may be that any small excess of and above that required for the precipitation of the cuprous sulfid. is neutralized by the excess sulfur dioxid present and thus converted into an inocuous condition. Since an excess of sulfur dioxid is maintained during the process, there is an excess present to take care of any small excess of hydrogen sulfid over an above that whichis required for the precip1- tation operation. Since sulfur dioxid gas is in many instances'a. waste product and a. nuisance, it is usually a product readily obtained in sutiicient amount at a minimum 0 expense. f

It will further be seen that the invention presents. from one aspect, a cyclic process in which sutiicieut sulfuric acid is regenerated from the copper sulfate to extract further amounts of copper ore; and that, in addition, where hydro en sulfid is used, there will be regenerate further amounts of sulfuric acid from the sulfur dioxidwhich will be available for use either for extracting cop )er ore or for the formation (if-hydrogen sultid, c. 1., by decomposing alkaline sulfids or iron sulfi i. This decomposition, moreover, may take place within the solution of copper sulfate when the decomposable sulfid is addedthereto, in the manner above described.

We claim 2- 1. The method of recovering copper from oxidized ores which comprises leaching the ore to obtain a solution containing the cop per as copper sulfate, and precipitating the copper from such solution as cuprous sultid 'in the presence. of sulfur dioxid and thereby amounts of, sulfuric regenerating further acid; substantially as described.

2. The method of recovering copper oxidized ores which comprises leaching the ore with sulfuric acid to form a copper sulfate solution, separating such solution from the gangue, precipitating the copper from such solution as cuprous sulfid in the resence of an excess of sulfur dioxid, and t ereby also regenerating sulfuric acid, an utilizing the sulfuric acid thus regenerated for leaching further amounts of ore; substantially as described.

3. The method of recovering coppcr froin oxidized ores which comprises leaching the ore to obtain a solution impregnating such solution with sulfur dioxid, and precipitating the copper in A possible cx1ilana-' from it of the copper assulthe presence of an excess of sulfur'dioxid as cuprous sultid; substantially as described.

4. The method ofrecovering cop er from oxidized ores which comprises leadhing the ore to obtain a solution of the copper as sulfate. impregnating such solution with sulfur dioxid. and precipitating the copper as cuprous sultid by means of h drogensulfid, an excess of sulfur dioxid eing maintained during the precipitation; substantially as described. v

5. The method of recovering cop er from oxidized ores which comprises 'leac iing' the ore to obtain a solution of copper as sulfate, impregnating such solution with sulfur dioxid, and precipitating the copper as cuprous 'sultid by means of hydrogen s'ul (1 generated within such solution from a suitable soluble sulfid; substantially as described.

6. The method of recovering copper precipitating the copper as-cu of sulfur dioxid;

copper from with hydrogen ini- 1 sulfate solutions which comprises.

the presence of an excess of sulfur dioxid I sufficient to insure precipitation of the copper'in the cuprous condition; substantially as described. j

v9. The method of recovering copper from copper sulfate solutions which comprises impregnating such solutions with sulfur dioxid and precipitating the copper therefrom as cuprous sulfid by treatment with hydrogen sultid eneratcd within the solution. an exf sulfur dioxid being present during the precipitation;

10. The method of recovering copper and removal of arsenic, a'ntimonv and other metals of the hydrogen sulfid group from zinc sulfate solutions or zinc electrolytes containing co per, and other metals of the hydrogen sul d group,

regnatin such solutions with sultur dioxid -and precipitating sultid group therefrom as sultids in the ous condition without precipitation of zinc sulfid; substantially as 11.

oxidized ores, which comprises leaching the ore with sulfuric acid to obtain a solution containing the copper as copper sulfate, presubstantially as describec which comprises im' the metals of thehydrogen -cipitating the copper from such solution as decon'iposable sulfids with art of the re-. cupi'cus sulfidvin t 'e presence of sulfur generated acid and thereby orming further 10 dicxid by adding hydrogen sulfid thereto, amounts of hydrogen sulfid; substantially as and thereby regenerating the sulfuric acid described. 7 5 combined with the copper; and added In testim y whereof We affix 01 1 s gn amounts of acid from-the sulfur dioxid, tulfes.

leaching further amounts of ore with plu't WILLIAM N. ROSSBERG. of the regenerated acid and decomposing GUY E. SHERIDAN. 

